Executive Summary

Diederik van Batenburg, Shell

This issue of SPE Res Eval & Engbrings you 10 papers that reflect areas of current activity and areas ofinterest in the industry. Three papers focus on pore-scale measurements and howthese can be upscaled to larger length scales. Two papers cover differentaspects of reservoir characterization, one paper discusses a history matchingworkflow, and another paper describes an enhanced-oil-recovery-(EOR) pilottest. The final three papers handle different aspects of tight and shale-gasreservoirs: core properties, simulation, and surveillance.

Pore-Scale Analysis and Upscaling

Permeability Upscaling for Carbonates From the Pore Scale by Use ofMultiscale X-Ray-CT Images presents porosity permeability transform-derivedpermeability values for carbonate samples that are sampled at differentresolutions. The resulting data are used to evaluate different upscalingapproaches.

Correlations Between NMR-Relaxation Response and Relative PermeabilityFrom Tomographic Reservoir-Rock Images demonstrates how the nuclearmagnetic resonance (NMR) response can also be used to estimate the effectivepermeability of mobile phases present in a sample. The estimated effectivepermeabilities correlate well with published Bentheim and Berea sandstonerelative permeability data.

The Use of Electromagnetic Mixing Rules for Petrophysical Evaluation ofDual- and Triple-Porosity Reservoirs provides a theoretical foundation fordifferent mixing rules that can be used for the evaluation of the porosityexponent for naturally fractured reservoirs represented by dual- andtriple-porosity models. Validity of these mixing rules is demonstrated bycomparison with core data from limestone, dolomite, and tight gasreservoirs.

Reservoir Characterization

Deepwater-Reservoir Characterization by Use of Tidal Signal ExtractedFrom Permanent Downhole Pressure Gauge demonstrates how tidal signalsextracted from highly accurate permanent downhole gauges that are now in use inmany deepwater developments can be used to estimate reservoir compressibilityand saturation changes.

Fluid Identification in Light Hydrocarbons With Use of NMR and DownholeFluid Analyzers--A Case Study presents a case history that demonstrates howthe integration of measurements from various tools can be used to improvefluid-type characterization, and consequently help to identify reservoircompartmentalization.

History Matching and Forecasting

An Integrated Model for History Matching and Predicting ReservoirPerformance of Gas/Condensate Wells presents a validation and case historyfor an integrated model to simulate gas condensate reservoir/well behavior. Themodel couples the material-balance equations for reservoir response, thetwo-phase pseudointegral pressure for near wellbore behavior, and outflowcorrelations for wellbore behavior.

Enhanced Oil Recovery

The Design and Execution of an Alkaline/Surfactant/Polymer Pilot Testreports on a tertiary alkaline surfactant polymer pilot flood implemented inthe Illinois basin in the US during 2010. The paper presents the currentinterpretation of the results of the pilot and useful lessons learned for otheroperators designing such pilots.

Tight and Shale Gas

Mercury Capillary Pressure Measurements on Barnett Core presentscapillary pressure measurements on 92 plugs from two Barnett shale wells. Thepermeability estimated from the capillary pressure date is in the 1-10nanodarcy range. Four different types of capillary pressure responses thatcorrelate with other rock properties can be distinguished. The study suggeststhat that the spatial distribution of rock properties, rather than the averageproperties, determines the quality of the wells.

High-Resolution Numerical Modeling of Complex and Irregular FracturePatterns in Shale-Gas Reservoir’s and Tight Gas Reservoirs presentsdetailed simulation results for horizontal wells with multiple hydraulicfractures in tight gas and shale-gas systems. The detailed model allows for theincorporation of irregular fracture patterns (e.g., fracture angularity,nonplanar fractures, and the effect of secondary “stress-release”fractures).

The Use of Microseismicity To Understand Subsurface-Fracture Systems andTo Increase the Effectiveness of Completions: Eagle Ford Shale, Texas showshow an array of geophones laid out radially around a well pad can be used todistinguish between different microseismic-source mechanisms, indicating afailure mechanism that is different for induced fractures than for reactivatedfaults. The resulting information can be used to optimize well spacing andcompletion design.

The included papers were all reviewed and ultimately approved in thepeer-review process. However, the conclusions presented in these papers are notcast in stone. Because sharing of knowledge and experiences is essential, SPEwelcomes further "discussion" of any paper published in any SPE journal.Therefore, please feel free to submit a discussion of a paper to SPE if youdisagree with interpretations or conclusions presented or if the authors andreviewers have missed publications that either support or invalidate results. Ilook forward to receiving such discussion letters.

Diederik van Batenburg
Co-Executive Editor of SPE Res Eval & Eng